The long-term goal of the TR&D 3 project is to develop high-impact, renewable, and open-source antibody reagents for cellular signaling and biomedical research. Specifically, we plan to focus on signaling events marked by important protein post-translational modifications (PTMs) such as phosphorylation and proteolytic zymogen activation events and their attendant protein conformational changes. While some antibodies do exist for specific phosphorylation sites, these antibodies are often unreliable, rarely renewable, and only available to a fraction of the modified sites. In addition, detecting functional forms of specific proteases has not been routinely possible in cells or in vivo due to the lack of conformationally selective antibodies. Furthermore, the industrialization of high-throughput recombinant antibody (rAb) selection and preparation has been thwarted by the absence of reliable robotic expression platforms. Thus, our immediate goals are to generate high-quality, open-source antibody reagents, by using novel phage display technologies and libraries developed by the UCSF Antibiome Center, to PTMs including: (i) phosphorylation sites, (ii) proteolytic neo-epitopes, and their attendant conformational changes, and (iii) alternative rapid antigen expression technologies such as in vitro transcription and translation (IVTT) that support all three TR&D projects. These goals compliment TR&Ds 1 and 2 by focusing on PTMs within key transmembrane proteins